1. Field of the Invention
This invention relates to a process for preparing organo-sulfonium halides. More particularly, it relates to a process for preparing trialkylsulfonium halides.
2. Related Art
Organo-sulfonium halides are useful in the preparation of pesticides and herbicides. Specifically, the sulfonium salts of N-phosphonomethylglycine have been found to be particularly effective herbicides against various types of grasses and other unwanted weeds.
In the preparation of the trialkylsulfonium salts of N-phosphonomethylglycine, the starting material is trialkylsulfonium hydroxide which is derived from the salt, trialkylsulfonium halide, in a number of different ways including electrolysis.
Sulfonium salts are, in part, known compounds, and methods for preparing all of these salts are shown in the art. U.S. Pat. No. 3,101,265 (Smutny et al., Aug. 20, 1963) discloses plant growth-modifying compositions comprising trialkylsulfonium salts and describes therein a method for preparing these salts. This method involves the reaction of a thioether, RSR' with a suitable aliphatic derivative of the anion of an inorganic acid i.e., an aliphatic halide, R"X or an aliphatic sulfate, R'"R""SO.sub.4.
The Encyclopedia of Chemical Technology, Kirk-Othmer, Volume 13, pages 440-441 describes the conventional synthesis of sulfonium compounds by the reaction of alkyl halides with sulfides, disulfides, thioaldehydes or thioketones.
However, novel ways of preparing these salts are sought because of their importance. It is an object of the present invention to provide an alternative method of producing organo-sulfonium salts and, in particular, trialkylsulfonium halides.
Other objects and advantages of the present invention are shown throughout the specification.